Long post...Ticking/knocking, no low end power
#1
01-28-2010, 01:33 PM
Long post...Ticking/knocking, no low end power
Here's the details: 1994 Camaro Z28 w/ 5.7L (P VIN code), automatic. Approx. 59,500 miles. No mods, stock vehicle with the exception of a drop-in K&N air filter. Car was mostly garage keep, maintenance for the most part, performed routinely. Car spent majority of it's day's in S. California, but is now a TN car.
Recent problems and work performed: 1) Sept. 09, car died while traveling approx. 20MPH, vehicle was towed the Chevy dealership. They found the water pump leaking/seeping, this caused the Opti to go bad. So the Opti, water pump, thermostat and related seals were replaced. While they were in there they did a tune-up consisting of new wire's and plugs. That was about $1800. 2)Dec. 09, The vehicle was leaking engine oil in the driveway, took it back in for a full seal replacement....$895, work performed by same dealership. 3) Dec.09, No Heat inside car, took back to same dealership, replaced heater core...$495. 4) Dec.09, car would just die/stall @ random, at any speed, and time, warm, cold, idling or under load....didn't matter. I would jiggle the harness under the MAF sensor and eventually it would run again. Wound up replacing the ICM, Coil and Coil wire to fix that one. Work was performed by myself.
Besides being on my 3rd trans mount and there is one major issue left to resolve and this is the reason for this email.
4) Right now the car is on jacks. The other day i went to pass a vehicle on the highway and punched the gas, i got a swift 2 gear downshift and the tach hit redline for about 2-3 seconds. I didn't notice any change in performance @ the time. When i got back into town, while stopped @ a light there was a loud and very distinct ticking or knocking noise coming from the engine bay. Upon the further inspection, i narrowed the noise coming from under the R/H head cover, somewhere. The ticking/knocking is present @ idle while the engine is warm only, however, always from 1500-3000 RPM, cold or warm. During acceleration the knocking noise will continue till about 3000 RPM's and along with the that, the vehicle has no power under the same RPM range. Once 3000 RPMs is reached, there is a power surge, almost as if the car was normal. It will start easily and idle smoothly. There is no smoke from the tailpipes and the engine oil is normal ( at the proper level, viscosity, with no metal on dipstick, doesn't smell burnt and shows now sighns of coolant).
What I've done: I've removed the R/H head cover and inspected the valvetrain. It was a cursory search. I didn't see any signs of bent valves, bent rods, or any other odddities. I did find some slightly loose rocker arms, which i tightened down ( by hand, i know, bad)until the horizontal play was eliminated. Then i put it all back. No change in status. Then i removed all the spark plugs and performed a compression check on all cylinders. All cylinders struck approx. 125 psi on the first stroke and topped @ approx. 200 psi @ the end of the 5th. There was no real difference between any of the cylinders. Compression was build quickly/sharply and held.
From here, i'm not sure where to go. i don't wanna start tearing into the head if not need be. But i'm suspecting a lifter or spring or something like that. The noise sounds as though it's coming from the upper end of the valvetrain but its to tell.. help will be greatly appreciated
Recent problems and work performed: 1) Sept. 09, car died while traveling approx. 20MPH, vehicle was towed the Chevy dealership. They found the water pump leaking/seeping, this caused the Opti to go bad. So the Opti, water pump, thermostat and related seals were replaced. While they were in there they did a tune-up consisting of new wire's and plugs. That was about $1800. 2)Dec. 09, The vehicle was leaking engine oil in the driveway, took it back in for a full seal replacement....$895, work performed by same dealership. 3) Dec.09, No Heat inside car, took back to same dealership, replaced heater core...$495. 4) Dec.09, car would just die/stall @ random, at any speed, and time, warm, cold, idling or under load....didn't matter. I would jiggle the harness under the MAF sensor and eventually it would run again. Wound up replacing the ICM, Coil and Coil wire to fix that one. Work was performed by myself.
Besides being on my 3rd trans mount and there is one major issue left to resolve and this is the reason for this email.
4) Right now the car is on jacks. The other day i went to pass a vehicle on the highway and punched the gas, i got a swift 2 gear downshift and the tach hit redline for about 2-3 seconds. I didn't notice any change in performance @ the time. When i got back into town, while stopped @ a light there was a loud and very distinct ticking or knocking noise coming from the engine bay. Upon the further inspection, i narrowed the noise coming from under the R/H head cover, somewhere. The ticking/knocking is present @ idle while the engine is warm only, however, always from 1500-3000 RPM, cold or warm. During acceleration the knocking noise will continue till about 3000 RPM's and along with the that, the vehicle has no power under the same RPM range. Once 3000 RPMs is reached, there is a power surge, almost as if the car was normal. It will start easily and idle smoothly. There is no smoke from the tailpipes and the engine oil is normal ( at the proper level, viscosity, with no metal on dipstick, doesn't smell burnt and shows now sighns of coolant).
What I've done: I've removed the R/H head cover and inspected the valvetrain. It was a cursory search. I didn't see any signs of bent valves, bent rods, or any other odddities. I did find some slightly loose rocker arms, which i tightened down ( by hand, i know, bad)until the horizontal play was eliminated. Then i put it all back. No change in status. Then i removed all the spark plugs and performed a compression check on all cylinders. All cylinders struck approx. 125 psi on the first stroke and topped @ approx. 200 psi @ the end of the 5th. There was no real difference between any of the cylinders. Compression was build quickly/sharply and held.
From here, i'm not sure where to go. i don't wanna start tearing into the head if not need be. But i'm suspecting a lifter or spring or something like that. The noise sounds as though it's coming from the upper end of the valvetrain but its to tell.. help will be greatly appreciated
#2
01-28-2010, 01:52 PM
did you try dropping the oil to see if there are metal flakes in it? i know when i lost a cam bearing, nothing showed up on the dipstick but it sure was a pretty sight when i dropped the oil
#4
01-28-2010, 03:52 PM
Join Date: Oct 2007
Location: The 'Burbs of Chicago
Posts: 18,306
First, if all you did was tighten up the rockers by hand, then your valve lash still is not set correctly.
But you might have a collapsed lifter. Check them all, especially the ones where the rockers were loose. With the valve cover off, turn the engine over and see how much up and down travel your rocker arms have, and see if any move noticeably less than others (measure with a ruler if you have to). Be sure to compare intake to intake and exhaust to exhaust, so that any differences in intake/exhaust cam lift doesn't throw you off. If you have one or more that isn't moving much, then back off that rocker to take the valve spring tension off and check the amount of lift again (at the pushrod). If movement now looks like normal, your lifter is bad. If movement didn't improve, you have a wiped cam lobe.
But you might have a collapsed lifter. Check them all, especially the ones where the rockers were loose. With the valve cover off, turn the engine over and see how much up and down travel your rocker arms have, and see if any move noticeably less than others (measure with a ruler if you have to). Be sure to compare intake to intake and exhaust to exhaust, so that any differences in intake/exhaust cam lift doesn't throw you off. If you have one or more that isn't moving much, then back off that rocker to take the valve spring tension off and check the amount of lift again (at the pushrod). If movement now looks like normal, your lifter is bad. If movement didn't improve, you have a wiped cam lobe.
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